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<td><h2>A visualization tool<br> for Gerber ©<br> and Excellon ©<br> files.</h2>
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<b>WARNING:</b><br>
This is a beta version. Access the web page <a href="http://www.mcn-audio.com/sharewares/index.html">here</a> for up-to-date versions.
Do not use for production purpose. Please report bugs to <a href="mailto:support@mcn-audio.com">support@mcn-audio.com</a>.
English is not my native language, be kind enough to report mistakes in
the documentation below and suggest improvements as well.</font>
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<b><h3>RESTRICTIONS FOR THIS VERSION</h3></b>
<u>Commands limitations:</u>
<br>
The following Gerber© commands should be parsed without errors, but will not be followed by any action:<br>
<br>
<div style="margin-left: 40px;">
AS Axis Select, IJ Image Justify, IF Include File, IO Image Offset, IP Image Polarity, IR Image Rotation, 
MI Mirror Image, KO Knock Out, LP Layer Polarity, OF Offset, PF Plotter Film, SR Step and Repeat.<br>
</div><br>
<u>Flash limitations:</u>
<br>
Pads with center hole will not display properly.<br>
<br>
<u>Macros limitations:</u>
<br>
Macros primitives CIRCLE, OUTLINE and POLYGON only are implemented. The number
of parameters must be less than 50. The name length must be less than 500 characters. 
The definition length must be less than 1024 characters. The variable modifiers should be processed properly. 
The mathematic parser for numerical operators is quite lazy for the time. 
Numerical operators add, subtract, divide and multiply should work, but equate is not supported.
<br>
<b><h3>Loading files</h3></b>
Load files using <i>File Open</i> menu or the shortcut (apple)+O. Multiple files selection is possible.<br> 
Add some new files to the current display with <i>File Add</i> menu or the shortcut (apple)+A.<br>
<b><h3>Controling the view</h3></b>
This is easily done if you have a dual button and scroll ball pointing device (Mighty Mouse to make it short).
The scroller controls the zoom. For panning, grab the view by keeping pressed the left button.<br>
On the top right of the application window, X and Y coordinates show the cursor postion. 
Relative measurements Delta X and Delta Y refer to the relative origin shown by the green cross. 
To move the relative origin to any location, use the single click right. 
The Delta D value is the distance between the relative origin and the actual mouse cursor position.
Coordinates unit can be changed between <i>mm</i> and <i>inch</i> in the <i>Preferences</i> menu.<br>
With a single button mouse, the Page-Up and Page-Down keys of the keyboard control the zoom.<br>
<b><h3>The Layers List</h3></b>
In the left part of the application window, a list shows the names of
the loaded layers. Layer visibility is controlled by the check box.
The layer on the top of the list is displayed on the top of the "z axis" stack (hiding
layers below if any). Drag an drop the names in the list to get the
arrangement you want. Black names go with Gerber© layers, blue
names go with Excellon© layers and red name with not-supported
formats or errors found during file parsing. A red name however doesn't
mean that the layer cannot be displayed, at least partially.<br>
<b><h3>Displaying Layer Information</h3></b>
In the layers list, double click the layer
name. This opens the Layer Information Sheet. There, you find:<br>
<ul>
<li>an apertures table, showing the apertures' codes, shapes, dimensions and
counts. Count values can be a traced (T) or flashed (F) number;</li>
<li>a format specification with <i>m.n</i>, <i>absolute</i> or <i>incremental</i>, 
<i>inch</i> or <i>millimeter</i>, <i>trailing</i> or <i>leading</i> settings;</li>
<li>a colour box to set the layer colour.</li>
</ul>
If the file format is RS-274X, the Extended Gerber©, most of the
settings are defined in the file header, and then cannot be changed
here.
<br>If the file format is RS-274D (the Standard Gerber©) or Excellon©,
settings can be changed and the apertures table can be edited. You must
reload the layer to see the effect of the changes. The layer will be
displayed correctly only if the values for <i>m.n</i> format, <i>coordinates</i>, <i>ommited zeros</i> and apertures' values are properly defined.<br>
<br>
First, define:<br>
<ul>
<li>the <i>m.n</i> specification;</li>
<li>the <i>absolute</i> or <i>incremental</i> mode of coodinates values;</li>
<li>the unit as <i>inch</i> or <i>millimeter</i>;</li>
<li>the suppression of <i>trailing</i> or <i>leading</i> zeroes.</li>
</ul>
Then reload the layer by clicking <i>Reload Layer</i> button. You should get a kind of "skeletton" display mostly showing tracks but no pad, 
however all dimensions should be accurate.<br>
<br> 
Then complete the aperture definition table, setting for each D (or T) code the shapes and the dimensions. 
<br>
Up to 100 apertures can be defined. The unit used to display apertures'dimensions is the one selected by the radio button.<br>
<b><h3>User Preferences</h3></b>
The User Preference sheet includes two panels:<br>
<ul>
<li>Gerber &amp; Excellon;</li>
<li>Rendering &amp; Data.</li>
</ul>
<b><u>Gerber &amp; Excellon</u></b>
<br>
For both data formats, these settings are used by default if no other
specification is included in the file. These settings should reflect
the requirements of the ECAD system you most frequently use.
Complete the aperture definition table, setting for each D code or T
code the shape and the dimensions according your ECAD standard aperture
wheel. Up to 100 apertures can be defined. The unit used to display
apertures' dimensions is the one chosen on the left.<br>
<br> 
Aperture table can aslo be completed using a definition file, by selecting the option <i>Get Codes from file</i>. 
This file must be an ASCII text format file, with space or tabulation separated values, following the syntax below:
<br><br>
<table style="width: 40%;" border="0" cellpadding="0" cellspacing="0">
  <tbody>
    <tr>
      <td>INCH</td>
      <td><br>
      </td>
      <td><br>
      </td>
      <td><br>
      </td>
    </tr>
    <tr>
      <td>D10</td>
      <td>CIRCULAR</td>
      <td>0.010</td>
      <td><br>
      </td>
</tr>
    <tr>
      <td>D11</td>
      <td>RECTANGLE</td>
      <td>0.020 <br>
</td>
      <td>0.300</td>
    </tr>
    <tr>
      <td>D12</td>
      <td>CIRCULAR</td>
      <td>0.020</td>
      <td><br>
      </td>
    </tr>
    <tr>
      <td>D13</td>
      <td>CIRCULAR</td>
      <td>0.010</td>
      <td><br>
      </td>
    </tr>
    <tr>
      <td>D14</td>
      <td>CIRCULAR</td>
      <td>0.020 <br>
</td>
      <td><br>
      </td>
    </tr>
    <tr>
      <td>...</td>
      <td>...</td>
      <td>...</td>
      <td>...</td>
    </tr>
  </tbody>
</table>
<br>
This file should include the token INCH or MM or METER or METRIC to set the unit. 
If not included, values are assumed to be Inch. 
If more than one unit token is included, the last one is used. 
This unit token may be placed before or after the apertures' defintions.<br>
Each line is parsed for a D or a T immediately followed by an interger
(immediately means without space in between).
If this D or T code is found, the rest of the line is analyzed,
searching for CIRCULAR, CIRCLE or&nbsp; CERCLE, or for RECTANGLE or
SQUARE to set the shape. According to the shape, one or two real values
(real means a decimal number, such 0.020) are expected.<br> 
Use <i>Browse</i> to find the file you want. 
The file name is displayed on a clear red background if it cannot be opened. 
If the file you've selected cannot be parsed, nothing will show in the apertures' table. 
<br><br>
<b><u>Rendering &amp; Data</u></b><br>
MCN Gerber Viewer relies on OpenGL© library to display the layers view.<br> 
Preferences here mostly control how OpenGL© is rendering the data, and some details about aperture files.<br>
<br>
<b>Create and use an aperture table associated to Gerber© files.<br></b>
This options only makes sense with Standard Gerber©, not embedding any
aperture information. To visualize such kind of files, you have to set
manually the format parameters, and fill in the aperture table
according to the aperture wheel of your ECAD system.
This is mainly a set and retry process: you adjust something and reload
the layer until the final result is reached. If you activate this
option, each time you load (or reload) the layer, an apertures file is
created in the current directory (the directory containing the Gerber©
file you are opening). The name of this file is formed by adding the
extension "apdef" to the Gerber© file name (for e.g. if the Gerber©
file is "artwork1.top" it will be "artwork1.top.apdef").
This file contains the D codes values you defined, following the syntax
described above. The next time you will open the same Gerber© file, you
will not need to enter these parameters again.<br><br>
<b>Always place Excellon© layers on the top.<br></b>
The drill layers are easy to be hidden by copper layers. Set this option to ensure these layers are placed on the top.<br><br>
<b>Show Excellon© layers using background colour.<br></b>
Set this option to get a more realistic view, drill mark then looking like holes.<br><br>
<b>Rendering approximation: Circles.<br></b>
OpenGL© don't draw circles but actually polygons. And a polygon pretty
looks like a circle if the number of segments used is high enough.
This setting lets you adjust between 10 and 30 this number of segments.<br><br>
<b>Rendering approximation: Track ends.<br></b>
On a real photoplotter, the shape of a track end is a half circle. For
the reason explained above, this setting lets you adjust between 4 and
30 the number of segments used to draw this half circle.<br><br>
<b>Rendering approximation: Circular interpolations.<br></b>
Circular interpolation is a primitive function of photoplotters to draw
arcs and circles.
For the reason explained above, this setting lets you adjust between 10
and 30 the number of segments used to draw this circular interpolation.<br>
<br>
nb. You have to reload the files to see the effect of these settings.
Please keep in mind that there is a compromize between the accuracy of
the view and the time required to create it. Increasing the number of
segments for circles rendering gives a better display, but at the
expense of a higher graphic processor load.
This will make the application less responsive during pan and resize of
the view.<br>
<br>
<b>Synchronize rendering updates to the vertical refresh.<br></b>
Even displaying a static image on a computer screen is a dynamic process. 
The graphic processor periodically redraws the image several times each second. 
If the image changes during the redraw time, some display artifacts may happend. 
Select this option to ensure that the application changes the image only between redraws.<br>
<br>
<b>Show mesh during pan and resize.<br></b>
Pan and zoom are extremely demanding tasks for the graphic processor. 
If the file you are viewing is heavy, or if you are facing limited graphic ressources, this option can help. 
When activated, the filling of graphic objects is simply forgotten: tracks turn to lines and pads turn to circles.   
This dramatically reduces the load applied to the graphic processor, and makes pan and zoom more dynamic.<br>
<br>
<b>Smooth display with multisampling.<br></b>
Select this option to improve the rendering. Multisampling uses an
additional pixel buffer to apply antialiasing on the edges of the
graphic primitives. This requires additional graphic processor
contribution, and more specificlly that the hardware of your computer
supports this OpenGL 1.3 feature.<br>
<br>
<b>Discard background color when printing or copying.<br>
</b>Select this option to get a clear background when printing or
copying the screen. Background will be white or transparent if you
paste the copy in a destination supporting transparency. <b><br>
</b>
<b><h3>Special thanks</h3></b>
<li>Special thanks to <b>Gerber Scientific</b>, the company founded in
the 1940s by Joseph Gerber, who opened the way of high accuracy optical
plotting systems.
Thank you for choosing a human-readable format and offering a good
documentation about it. Learn more about Gerber Scientific here:
www.gerberscientific.com.</li><br>
<li>Special thanks to OpenGL people for providing a powerfull library.</li><br>
<li>Special thanks to Apple for OpenGL intergration, Cocoa frameworks and offering XCode.</li>
<b><h3>References</h3></b>
All product names cited are trademarks or registered trademarks of their respective owners.<br>
<br>
<b>Gerber©</b> is a registered name of Barco Graphics N.V., Gent, Belgium.<br>
Specification of the format can be found on Barco ETS web site: www.barco.com.<br>
<br>
Barco ETS <br>
Tramstraat 69 <br>
B-9052 Gent <br>
<br>
<b>Excellon©</b> is a registered name of Excellon Automation Co.<br>
Specification of the format can be found on Excellon Automation web site: www.excellon.com.<br>
<br>
Excellon automation Co.<br>
20001 S. Rancho Way, Rancho Dominguez, CA 90220<br>
Phone: +1 310.668.7700&nbsp;&nbsp;&nbsp; Fax: +1 310.668.7800 <br>
<br>
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© MCN AUDIO Sofwares 1995 - 2009   /   René LOUISOR-MARCHINI
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